The present invention relates to a wireless communication apparatus and a wireless communication program which can be applied to, for example, smart meters.
IEEE 802.15.4 g (hereinafter referred to as “Non-Patent Document 1”) defines a MAC (Media Access Control) protocol standard (hereinafter simply “Normal 15.4 Protocol”) for typical wireless data communication. IEEE 802.15.4e (hereinafter referred to as “Non-Patent Document 2”) defines an extended standard for adopting the above standard to various applications, with CSL (Coordinated Sampled Listening) and RIT (Receiver Initiated Transmission) being defined as standards for low-power data communication within such extended standard. An extended standard for low-power data communication is referred to below as “CSL Protocol”.
FIG. 7 is a state transition diagram according to Normal 15.4 Protocol. With Normal 15.4 Protocol, there is only one possible state when standing by for reception, the “15.4 reception standby state” ST11. When performing transmission, the state becomes the “15.4 transmission state” ST12 and frame transmission is carried out. When a frame is being received, the state changes to the “15.4 reception state” ST13. Note that the initial state is the “15.4 reception standby state” ST11.
FIG. 8 is a state transition diagram relating to CSL Protocol. In CSL Protocol, there are two states when standing by for reception, the “CSL reception standby state” ST21 and the “CSL reception idle state” ST22, with the state changing between the two states ST21 and ST22 at fixed intervals. For transmission, the state becomes the “CSL transmission state” ST23 and frame transmission is carried out according to a method unique to CSL so that the frame arrives when the transmission destination node is in the “CSL reception standby state” ST21. When frame reception is being carried out, the state becomes the “CSL reception state” ST24. The “CSL reception standby state” ST21 and the “CSL reception idle state” ST22 differ as to whether a frame can be received from another node. The initial state is the “CSL reception idle state” ST22.
Normal 15.4 Protocol and CSL Protocol are different MAC protocols where the frame transmission method, the operation when standing by for reception, and the like all differ. This means that communication between a node that uses Normal 15.4 Protocol and a node that uses CSL Protocol is not possible.
IEEE 802.15.4 g was established as a wireless communication standard for smart meters. Since information from a smart meter is valuable, such information is gathered by a data center or the like via a plurality of networks such as FAN (Field Area Networks) and HAN (Home Area Networks).
A FAN is a large-scale network where latency on the MAC layer is important, and therefore Normal 15.4 Protocol is used. Conversely, a HAN uses CSL Protocol due to the importance of the low power function. If it is necessary for a smart meter to belong to both networks, the smart meter will need to be compatible with a plurality of MAC protocols.
When a plurality of MAC protocols are to be used by a single wireless node (a wireless communication apparatus, such as a smart meter), as shown in FIG. 9 it is conventional to equip a wireless node 100 with a wireless communication unit 101-1, 101-2 for each protocol to be used. One reason for this is that it is difficult to carry out communication using a plurality of MAC protocols using a single wireless communication unit. It is not conventional to have a single wireless communication unit operate according to a plurality of MAC protocols. If the wireless communication units 101-1, 101-2 are provided for the respective MAC protocols, the wireless communication units 101-1, 101-2 can operate independently and as a result it becomes possible for a single apparatus to simultaneously use a plurality of MAC protocols.
The configuration and operation of FIG. 9 will now be described in brief.
The wireless node 100 includes an apparatus control unit 106 and the two wireless communication units 101-1, 101-2. The wireless communication units 101-1, 101-2 shown in FIG. 9 are written as parts that carry out processing on the MAC layer and the physical layer. The first wireless communication unit 101-1 includes a Normal 15.4 Protocol control unit 102 and a frame communication unit 103. The second wireless communication unit 101-2 includes a CSL Protocol control unit 104 and a frame communication unit 105.
The apparatus control unit 106 carries out various control of the entire node, but the following description will focus on control related to the characteristics of the present invention (i.e., description of control that is unrelated to the characteristics of the present invention is omitted). When a frame is to be transmitted, the apparatus control unit 106 fulfills a function of determining whether transmission according to Normal 15.4 Protocol or transmission according to CSL Protocol is to be carried out (as one example, information on compatible MAC protocols of other nodes is managed and the MAC protocol to be used is decided in accordance with the destination node of the present transmission frame) and passing the frame to be transmitted to the Normal 15.4 Protocol control unit 102 or the CSL Protocol control unit 104 in accordance with the determination result, a function of receiving a frame received according to Normal 15.4 Protocol from the Normal 15.4 Protocol control unit 102, and a function of receiving a frame received according to CSL Protocol from the CSL Protocol control unit 104.
Under the control of the apparatus control unit 106, the Normal 15.4 Protocol control unit 102 fulfills a function of requesting the frame communication unit 103 to carry out frame transmission according to Normal 15.4 Protocol and a function of processing a frame received by the frame communication unit 103 according to Normal 15.4 Protocol and notifying the apparatus control unit 106 of necessary information. State transitions of the Normal 15.4 Protocol control unit 102 are as shown in FIG. 7 described above.
Under the control of the apparatus control unit 106, the CSL Protocol control unit 104 fulfills a function of requesting the frame communication unit 105 to carry out frame transmission according to CSL Protocol and a function of processing a frame received by the frame communication unit 105 according to CSL Protocol and notifying the apparatus control unit 106 of necessary information. State transitions of the CSL Protocol control unit 104 are as shown in FIG. 8 described above.
The frame communication unit 103 and the frame communication unit 105 respectively fulfill a function of transmitting and receiving frames that satisfy the frame formats (see FIG. 4, described later) used by Normal 15.4 Protocol and CSL Protocol.